Classifications

• • C—CHEMISTRY; METALLURGY
  • C09—DYES; PAINTS; POLISHES; NATURAL RESINS; ADHESIVES; COMPOSITIONS NOT OTHERWISE PROVIDED FOR; APPLICATIONS OF MATERIALS NOT OTHERWISE PROVIDED FOR
  • C09K—MATERIALS FOR MISCELLANEOUS APPLICATIONS, NOT PROVIDED FOR ELSEWHERE
  • C09K19/00—Liquid crystal materials
  • C09K19/04—Liquid crystal materials characterised by the chemical structure of the liquid crystal components, e.g. by a specific unit
  • C09K19/42—Mixtures of liquid crystal compounds covered by two or more of the preceding groups C09K19/06 - C09K19/40
• • C—CHEMISTRY; METALLURGY
  • C09—DYES; PAINTS; POLISHES; NATURAL RESINS; ADHESIVES; COMPOSITIONS NOT OTHERWISE PROVIDED FOR; APPLICATIONS OF MATERIALS NOT OTHERWISE PROVIDED FOR
  • C09K—MATERIALS FOR MISCELLANEOUS APPLICATIONS, NOT PROVIDED FOR ELSEWHERE
  • C09K19/00—Liquid crystal materials
  • C09K19/04—Liquid crystal materials characterised by the chemical structure of the liquid crystal components, e.g. by a specific unit
  • C09K19/06—Non-steroidal liquid crystal compounds
  • C09K19/08—Non-steroidal liquid crystal compounds containing at least two non-condensed rings
  • C09K19/30—Non-steroidal liquid crystal compounds containing at least two non-condensed rings containing saturated or unsaturated non-aromatic rings, e.g. cyclohexane rings
  • C09K19/3001—Cyclohexane rings

Definitions

• the TN effect is usually used as the electro-optical effect.
• TFTs made from compound semiconductors such as CdSe or TFT's based on polycrystalline or amorphous silicon The latter technology is being worked on with great intensity worldwide.
• the TFT matrix is applied to the inside of one glass plate of the display, while the other glass plate carries the transparent counter electrode on the inside. Compared to the size of the pixel electrode, the TFT is very small and practically does not disturb the image.
• This technology can also be expanded for full color images, with a mosaic of red, green and blue filters is arranged such that one filter element each is opposite a switchable picture element.
• the TFT displays usually work as TN cells with crossed polaristors in transmission and are illuminated from behind.
• MLC displays of this type are particularly suitable for TV applications (for example pocket TVs) or for high-information displays in automobile or aircraft construction.
• difficulties arise with MLC displays due to insufficiently high specific resistance of the liquid crystal mixtures [TOGASHI, S., SEKIGUCHI, K., TANABE, H., YAMAMOTO, E., SORIMACHI, K. , TAJIMA, E., WATANABE, H., SHIMIZU, H., Proc. Eurodisplay 84, Sept. 1984: A 210-288 Matrix LCD Controlled by Double Stage Diode Rings, p. 141 ff, Paris; STROMER, M., Proc.
• the invention has for its object to provide MLC displays that do not have the disadvantages indicated above or only to a lesser extent and at the same time have very high specific resistances.
• the invention also relates to corresponding liquid crystal mixtures, in particular for use in MLC displays.
• the mixtures are also suitable for many other applications, such as TN, STN or OMI.
• the dielectric positive ( ⁇ ⁇ 1.5) components usually carry terminal cyan groups.
• the liquid crystal mixture consists essentially of components A, B and C, or A and B.
• Liquid crystal mixtures containing nitrile-containing and nitrile-free fluorinated compounds are particularly preferred, the latter preferably corresponding to the formulas IIa to IIf, where X is F, Cl, -CF3, -CHF2, -OCF3, -OCHF2, -OCF2CF2H or -OC2F5.
• the ratio of nitrile-free: nitrile-containing compounds from component B is preferably> 1: 1, in particular> 2: 1. Particularly preferred ranges are 2.5: 1 to 6: 1.
• liquid crystal mixtures whose component B consists essentially of nitrile-free, fluorinated compounds are very particularly preferred.
• the abovementioned preferred compounds of the formulas IIa to IIf are preferably used.
• liquid crystal mixtures whose component B contains terminally chlorinated compounds.
• Component B can also contain 4-nucleus compounds, for example according to the formulas IIc to IIf, in which one of the rings X1 to A3 is double.
• the mixtures contain compounds with terminal nitrile in a proportion of 0 to 50% by weight in component B.
• Mixtures which contain no compounds with terminal nitrile are particularly preferred.
• groups such as -OCF3, -OCHF2, -OCF2CF2H or -OC2F5 stabilize ions in the displays significantly less than -OCH3 or -OC2H5.
• aliphatic alkoxy compounds of the formulas III and IV).
• the mixtures according to the invention preferably have a specific resistance at 20 ° of ⁇ 10 12 ⁇ . cm, particularly preferably> 10 13 ⁇ . cm.
• the mean ⁇ is preferably ⁇ 7, particularly preferably ⁇ 5.
• the dielectric anisotropy values of the individual compounds of components A to D are determined at 20 ° by extrapolation from a polar mixture (containing 24% p-trans-4-propylcyclohexylbenzonitrile, 36% p-trans-4-pentylcyclohexylbenzonitrile, 25% p- trans-4-heptylcyclohexylbenzonitrile and 15% 4-cyano-4 ′ - (trans-4-pentylcyclohexyl) biphenyl), if the compound to be determined contains a dipole in the longitudinal axis of the molecule, or from a neutral mixture (containing 22% trans-1-p-ethylphenyl-4-propylcyclohexane, 20% trans-1-p-methoxyphenyl-1-propylcyclohexane, 15% trans-1-p-ethoxyphenyl-4-propylcyclohexane, 19% 4-ethyl-4- (trans -4-propyl
• the liquid crystal mixtures according to the invention make it possible at the same time to achieve a high value for the specific resistance at low viscosities, as a result of which excellent MKF displays can be achieved.
• the MFK displays according to the invention preferably operate in the first transmission minimum according to Gooch and Tarry [C.H. Gooch and H.A. Tarry, electron. Lett. 10, 2-4, 1974; C.H. Gooch and H.A. Tarry, Appl. Phys., Vol. 8, 1575-1584, 1975], where in addition to particularly favorable electro-optical properties such as e.g.
• the viscosity at 20 ° C is preferably ⁇ 25 mPa.s.
• the nematic phase range is preferably at least 70 °, in particular at least 80 °. This range preferably extends at least from -20 ° to + 70 °.
• the individual compounds of the formulas I to IV and their sub-formulas which can be used in the MLC displays according to the invention are either known, or they can be prepared analogously to the known compounds.
• Preferred liquid crystal mixtures which can be used according to the invention preferably contain a total of preferably 10% to 70%, in particular 10% to 40%, of compounds of the formula I. If component B is not predominantly composed of strongly dielectric positive nitrile components, but predominantly only weakly dielectric positive Compounds A, for example, contains compounds such as the fluorinated compounds given below, component A may be completely omitted and the mixtures according to the invention in this particular embodiment are based only on component B and possibly component C.
• liquid crystal mixtures whose component B contains one or more compounds selected from the group consisting of compounds of the formulas IIa to IIf, wherein R n-alkyl or n-alkenyl with up to 9 carbon atoms, X Cyan, -NCS, F, Cl, -CF3, -CHF2, -OCF3, -OCHF2, -OCF2CF2H or -OC2F5, and the rings A1, A2 and A3 each independently mean 1,4-phenylene, 2- or 3-fluoro-1,4-phenylene, 2,3-difluoro-1,4-phenylene, trans-1,4-cyclohexylene or 1,4-cyclohexenylene.
• Component B preferably contains compounds of the formulas IIa to IIf, in which X is cyan, and compounds of the formulas IIa to IIf, in which X is -NCS, F, Cl, -CF3, -CHF2, -OCF3, -OCHF2, -OCF2CF2H or -OC2F5 means, and the proportion of the cyan compounds in component B is 0 to 50 wt.%.
• component B contains no compounds of the formulas IIa to IIf in which X is cyan.
• X is preferably F, Cl, CF3, -OCF3, -OCHF2 or CHF2.
• the rings A1, A2 and A3 each preferably mean independently of one another trans-1,4-cyclohexylene or 1,4-phenylene.
• one of the rings A1, A2 and A3 is 2- or 3-fluoro-1,4-phenylene or 2,3-difluoro-1,4-phenylene.
• the ring connected to X is preferably 1,4-phenylene, which can optionally also be mono- or disubstituted by fluorine.
• A2-X or A3-X is preferably a group selected from the formulas (a) to (h): with (a), (b), (d), (f), (g) and (h) being particularly preferred.
• R in each case denotes n-alkyl or n-alkenyl with up to 9 carbon atoms.
• Y and Z are each independently H or F, but preferably one or two of the radicals Y and Z are fluorine.
• X is preferably F, Cl, -CF3-, -OCF3 or -OCHF2.
• Component B preferably makes up 10% to 100%, in particular 20% to 80%, of the mixtures according to the invention.
• Component A preferably contains one or more compounds selected from the group consisting of II1 to II7: wherein R1 and R2 have the meaning given in claim 1.
• Component A preferably additionally contains one or more compounds selected from the group consisting of II8 to II20: wherein R1 and R2 have the meaning given in claim 1 and the 1,4-phenylene groups in II8 to II17 can each be substituted one or more times independently of one another by fluorine.
• Component A preferably also additionally contains one or more compounds selected from the group consisting of II21 to II25: wherein R1 and R2 have the meaning given in claim 1 and the 1,4-phenylene groups in II21 to II25 can each be substituted one or more times independently of one another by fluorine.
• mixtures of this type are preferred, whose component A contains one or more compounds selected from the group consisting of II26 and II27: wherein C r H 2r + 1 is a straight-chain alkyl group with up to 7 C atoms.
• liquid crystal mixtures which, in addition to components A, B and C, additionally contain one or more compounds selected from the group consisting of III and IV: wherein R1 and R2 have the meaning given above, and / or one or more compounds selected from the group consisting of V and VI wherein R1 and R2 have the meaning given above, and / or contain one or more compounds selected from the group consisting of VII to XI wherein R1 and R2 have the meaning given above and s is 0 or 1.
• the proportion of the compounds of the formulas III to XI in the mixtures according to the invention can be seen from the following table: Sum of compounds III and IV: 0% to 40%, preferably 10% to 30% Sum of compounds V and VI: 0% to 40%, preferably 5% to 20% Sum of compounds VII to XI: 0% to 20%, preferably 5% to 15%
• component D is preferably 5 to 12% by weight, preferably two or more homologs of component D are used.
• Component D can contain the following preferred compounds D1, D2 and D3: n and m are each independently 2, 3, 4 or 5. Preferred combinations for n and m are: 3/3, 3/4, 3/5, 2/3, 4/3, 5/3, / 3 / 2nd D1 is particularly preferred.
• mixtures according to the invention which preferably consist essentially of the preferred compounds indicated for components A to D, may also contain further compounds not explicitly mentioned here. In many cases, however, this results in less favorable properties. The person skilled in the art can easily determine whether and if so in what amounts further compounds can be used.
• the construction of the MFK display according to the invention from polarizers, electrode base plates and electrodes with surface treatment corresponds to the design customary for such displays.
• the term of the conventional design is broad here and also includes all modifications and modifications of the MLC display, in particular also matrix display elements based on poly-Si TFT or MIM.
• liquid crystal mixtures which can be used according to the invention are prepared in a manner which is conventional per se.
• the desired amount of the components used in smaller amounts is dissolved in the components which make up the main constituent, advantageously at elevated temperature.
• solutions of the components in an organic solvent e.g. in acetone, chloroform or methanol, and to remove the solvent after thorough mixing, for example by distillation.
• the dielectrics can also contain further additives known to the person skilled in the art and described in the literature. For example, 0-15% pleochroic dyes or chiral dopants can be added.
• composition of the mixtures of Examples 1 to 25 is given below, the individual compounds being coded as follows: PCH-301: trans-1-p-methoxyphenyl-4-propylcyclohexane CCH-301: trans, trans-4-methoxy-4'-propylcyclohexylcyclohexane CBC-33F: 4,4'-bis (trans-4-propylcyclohexyl) -2-fluorobiphenyl CBE-55F: 4,4'-bis (trans-4-pentylcyclohexyl) -2-fluorobiphenyl CBC-53F: 4- (trans-4-pentylcyclohexyl) -4 ′ - (trans-4-propylcyclcohexyl) -2-fluorobiphenyl CBC-33: 4,4'-bis (trans-4-propylcyclohexyl) biphenyl CBC-55: 4,4'-bis (trans-4-pentylcyclohexyl)

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• Chemical & Material Sciences (AREA)
• Crystallography & Structural Chemistry (AREA)
• Engineering & Computer Science (AREA)
• Materials Engineering (AREA)
• Organic Chemistry (AREA)
• Liquid Crystal Substances (AREA)
• Liquid Crystal (AREA)

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Citations (8)

• 1989
  • 1989-08-22 DE DE3927674A patent/DE3927674A1/de not_active Withdrawn
• 1990
  • 1990-08-08 EP EP90115213A patent/EP0414048B1/fr not_active Expired - Lifetime
  • 1990-08-08 DE DE59007436T patent/DE59007436D1/de not_active Expired - Lifetime
  • 1990-08-21 KR KR1019900012867A patent/KR0160776B1/ko not_active IP Right Cessation
  • 1990-08-22 JP JP2219141A patent/JP3065092B2/ja not_active Expired - Lifetime

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